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Energy Efficient Retrofits
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New buildings account for a relatively small percentage of the energy used in the building sector. Retrofitting existing housing and commercial/industrial facilities is an important goal in terms of energy savings. It is also a complex endeavor, with many factors to consider, from preserving historic features to controlling costs.
The following articles and reports discuss a wide variety of materials, situations and techniques that may be encountered when undertaking an energy-efficient retrofit. As well, many case studies are provided to illustrate how to do retrofits right.
Attics should be air sealed prior to adding insulation. Adding insulation alone does not save much energy and can lead to health and durability problems. The intent of this guide is to provide information for the preparation work necessary prior to adding attic insulation.
What we learned from updating a 16-year-old deep-energy retrofit. Reprinted with permission from Fine Homebuilding, February/March 2012, pages 55-59.
Can a 150-year-old house approach zero energy use? Three case studies point the was from the 19th to the 21st century. Reprinted with permission from Fine Homebuilding, April/May 2008, pages 51-57.
This paper is from the proceedings of the Thermal Performance of the Exterior Envelopes of Whole Buildings XI International Conference, December 5-9, 2010 in Clearwater, Florida. The issues of climate change, energy security, and economics are all strong drivers for improving energy efficiency levels in a variety of sectors. In residential construction, although some inroads have been made in new houses, the stock of existing housing represents a huge opportunity for energy retrofits. The vanguard of these efforts has been pushing toward retrofitting very high insulation levels (i.e., “superinsulation,” or “deep energy retrofits”). Several cold-climate residential retrofit projects have been completed using an exterior insulation approach on light-frame above-grade walls. This type of retrofit is a reasonable step if a recladding of the building is already being done for aesthetic or ongoing maintenance reasons. The methods demonstrated here result in walls with insulation levels in the R-35 to R-40 range. This paper presents many of the lessons learned from these experiences, including overall enclosure strategies, such as air barriers, drainage planes, and moisture control. Several case-specific solutions to particular problems are described, including exterior air barrier approaches, wall sill replacement, and several approaches dealing with window penetrations. In addition, detailing recommendations and economic analysis of these measures are presented. Hygrothermal simulations were run to evaluate the changes in sensitivity to moisture intrusion due to these retrofit measures.
This paper is from the proceedings of the Thermal Performance of the Exterior Envelopes of Whole Buildings XI International Conference, December 5-9, 2010 in Clearwater, Florida. This paper summarizes some of the limitations of the various approaches to assessing the freeze-thaw resistance of brick masonry units and presents a detailed methodology for using frost dilatometry to determine the critical degree of saturation of brick material. Test results are presented for bricks from several historical load-bearing masonry. Recommendations are made for applying this approach together with hygrothermal model in the design of retrofit insulation projects.
Load-bearing masonry buildings are a significant portion of the existing building stock. Given the Building America goals of reducing home energy use by 30%-50% (compared to 2009 energy codes for new homes and pre-retrofit energy use for existing homes), insulation and air sealing of mass masonry walls will need to be a component of this work if mass masonry residential buildings are to be addressed.
This project examines a large scale renovation project within a 500 unit, 1960’s era subsidized urban housing community. The development comprises low-rise and mid-rise structures both of which exhibit exposed concrete frames with uninsulated masonry infill walls. The renovation project has a particular focus on indoor environmental quality and energy performance. The nature of occupied rehabilitation necessarily limited the scope of work implemented within apartment units. This research focuses on the airflow control and window replacement measures implemented as part of the renovations to the low-rise apartment buildings.
Building Science Corporation seeks to further the energy efficiency market for cold climate, New England area retrofits by supporting projects based on solid building science fundamentals and verified implementation. The utility company National Grid engaged BSC as a partner to develop guidelines for its Deep Energy Retrofit Pilot Program. In addition to guideline development, BSC has acted as a consultant for these projects and others following similar retrofit strategies.
Basements can account for up to one quarter of the typical energy consumption in a house. Therefore, insulating foundations is a critical measure for achieving high performance buildings. This is important in both new construction and retrofits of existing buildings. The fundamental problems and “best practice solutions” for moisture-safe basement insulation have been well established. However, many foundations are damp (either due to bulk water or capillary “wicking” of moisture) or of a type of construction that is not easy or straightforward to insulate (such as rubble foundations). Damp foundation repair methods can be “leveraged” to provide energy efficiency benefits. An example of this “hybrid” approach is spray foam insulation, which can be an effective means of liquid phase water control (leaking basement), vapor phase water control (diffusion and air leakage transported condensation) as well as an effective insulation.
Through discussion of five case studies (test homes), this project evaluates strategies to elevate the performance of existing homes to a level commensurate with best-in-class implementation of high performance new construction homes. The test homes featured in this research activity participated in Deep Energy Retrofit (DER) Pilot Program sponsored by the electric and gas utility National Grid in Massachusetts and Rhode Island. Retrofit strategies are evaluated for impact on durability and indoor air quality in addition to energy performance.
Building Science Corporation (BSC) has been working with Byggmeister, a partner on the Building America (BA) team, on retrofit projects under the BA program. Byggmeister is a local design-build firm that specializes in energy efficient retrofits and new construction. The Duclos, Eldrenkamp and Panish Energy Group (DEEP Energy Group), which is associated with Byggmeister, conducts design-phase energy analysis and monitors completed projects. The Byggmeister multifamily test home located in Jamaica Plain, Massachusetts (Jamaica Plain or J.P. Three-Family) is a three-story brick row house . The test home is examined with the goal of producing a case study that could be applied to similar New England homes. Basic areas of research that this report is expected to contribute include finding the combination of measures that are feasible, affordable, and suitable for this type of construction and acceptable to homeowners.
This research project developed baseline engineering analysis to support the installation of thick layers of exterior insulation (2” to 8”) on existing masonry walls and wood framed walls through the use of wood furring strips (fastened through the insulation back to the structure) as a cladding attachment location. Furthermore, water management details necessary to connect the exterior insulated wall assemblies to roofs, balconies, decks, and windows were created to provide guidance on the integration of exterior insulation strategies with other enclosure elements.
This project examines implementation of advanced retrofit measures in the context of a large-scale weatherization program and the archetypal Chicago, Illinois, brick bungalow. In response to the apparent weatherization program limitations with respect to homes with masonry bearing wall construction, this research project examines two distinct strategies for insulating and air sealing the top of houses. One strategy applies best practice air sealing methods and a standard insulation method to the attic floor. The other strategy creates an unvented roof assembly using materials and methods typically available to weatherization contractors.
